The present invention relates in general to heated tools and, in particular, to a new and useful heated tool having a support for engaging the opposite side of parts to be connected together by heat, the support also being heated to reduce the heat gradient across the parts. The heating tools may either be moved to the objects to be treated, or connected, or mounted in a fixed position with the object to be treated, or connected being brought to the heated tool.
Thermal energy is either supplied to the objects to be treated, or connected by radiant heating from heated surfaces of the tool, or by direct thermal contact between the heated tool and the object. A controlled force is usually applied against the object by the heated tool. An additional thermal conductive material may be used to increase heat flow from the heated tool to the object. Flux, for example, may be provided, for increasing the transfer of heat and for reducing oxidation during the thermal process.
Such tools may supply heat either continuously or during selected time periods only. Heat may be applied during heating pulses, which may be activated or controlled by various external conditions, for example, by forcing the heated tool against the object to be heated or connected.
Various sources of heat are known for heating the heated tool to a variety of selected temperatures. Hot gases and/or electric current, for example, may be used for heating specified heat supplying areas or surfaces of the tool.
For the present invention, it is preferable to utilize the flow of electrical current through a heated tool for heating the tool. This permits controlled pulse-heating, featuring fast heating rates, as well as precise temperature control at various areas of the tool.
A known generally U-shaped heated tool is disclosed in German Pat. No. 2,848,519. This heated tool is mounted to holders, either using screws or by welding. This keeps the heat supplying areas of the tool in position and further is used to provide electrical connectors for feeding electrical heating current to the tool. Such tools can be manufactured using sheet metal designs (see German Pat. Nos. 3,144,048.7, 3,137,859.5 and 3,137,860.9 to the present inventor). These heated tools can also be machined from solid materials.
The use of heated tools for heating and connecting thin parts having high thermal conductivity poses special problems. To accommodate the force applied by the heated tools, the thin parts must be mechanically supported. The presence of a mechanical support, however, produces a large thermal load on the heated tool and produces a large temperature gradient across the thin part.